Brake



J. SNEED May 9, 1939.

BRAKE Original Filed Nov. 18, 1931 3 Sheets-Sheet l INVENTOR Jaw Jyae'aATTORNEY.

5 7 4 3 3 M .0 5 4 f 7 \./.l 4 5 Z a 6 0 y 1939- J. SNEED 2,157,272

BRAKE Qriginal Filed Nov. 18, 1951 3 Sheets-Sheet 2 INVENTOR.

BY 7 dom v dye-0 ATTORNEY.

May 9, 1939. J. SNEED 2,157,272

BRAKE Original Filed NOV. 18, 1931 3 Sheets-Sheet 3 INVENTOR /0/ 1/j/vzzp ATTORNEY.

Patented May 9, 1939 ,157,212 name John Sneed, Grosse Pointe Shores,Mich., assignor to The Midland. Steel Products Company, Cleve;-

land, Ohio, a corporation of Ohio, trustee for Steeldraulic BrakeCorporation, a corporation of Michigan Original application November 18,1931, Serial Divided and this applicationSeptember 4, 1936, Serial No.99,445

4 Claims.

This invention relates to friction brakes, and more particularly to animproved brake construction especially suitable for use uponautomotivevehicles. The invention has for one of its objects provision of animproved vehicle brake, of the servo type, in which greater, moreefiective and more easily controllable braking force is available withthe expenditure of litt effort by the operator.

A further object of the invention is the provisionof a friction brake ofa self adjusting device furnishing means for mechanically taking up wearof the brake linings, such as is caused by continued use of the brake,thus eliminating the necessity of special adjustment for such purpose.

Another object of my invention lies in the provision of such anautomatic take-up device, operable in response to ordinary utilitarianactuation of the brake, to provide automatic adjustment of the brake tocompensate for wear, which device will be simple and reliable inoperation and of sturdy construction.

A still further object of this invention is the provision of a brakeconstruction, possessing the above outlined advantages, which is ofsimple and inexpensive construction,

Other objects and advantages will be apparent from the followingdescription, wherein reference is made to the accompanying drawingsillustrating preferred embodiments of my invention, and wherein similarreference numerals designate similar parts throughout the several views.

In the drawings:

Figure 1 is a sectional elevational view taken substantially verticallythrough a brake incorporating one form of my invention, looking towardthe brake apron.

Figure 2 is a detail sectional view taken substantially on the line 2-2of Figure 1 and looking in the direction of the arrows.

Figure 3 is a detail sectional view taken substantially on the line 3-3of Figure 1 and looking in the direction of the arrows.

Figure 4 is a detail sectional view taken substantially on the line 4-4of Figure 1 and looking in the direction of the arrows.

Figure 5 is a fragmentary plan view of a portion of my preferred brakeband construction, taken looking substantially in the direction of thearrow designated 5 in Figure 1, and with the brake drum removed.

Figure 6 is a fragmentary perspective view of the same portions of mypreferred brake band construction, the brake lining and its supportingring being partly broken away to afford better view of the webconstruction.

Figure '7 is a detail sectional view taken substantially on the line'l-l of Figure 1 and looking in the direction of the arrows.

Figure 8 is a sectional elevational view similar I to Figure 1, butpartly broken away, of a somewhat modified form of my invention.

Figure 9 is a detail sectional view taken substantially on the line 9-9of Figure 8 and. looking in the direction of the arrows.

Figure 10 is a fragmentary plan view of a modified form of automaticadjusting mechanism.

Figure 11 is a detail sectional view thereof taken substantially on theline llll of Figure 10, and

Figure 12 is a comparative diagrammatic representation of theproportionate braking effort obtainable by servo action with my improvedbrake construction, as compared to that obtainable by similar action inan ordinary selfenergizing brake of eiilcient and well known design,having contacting braking surfaces closely approaching 360".

This application is a division of my co-pending application for Frictionbrake, Serial No. 575,833 filed November 18, 1931, now Patent No.2,054,470, assued September 15, 1936.

Referring now to the drawings: Reference character i5 indicates a brakedrum, which may be of the usual or any desired construction, being hereshown interiorly provided with a braking surface adapted to be contactedby brake lining i6, carried by a one-piece split annular brake band H.The brake band is relatively flexible except where reinforced by webs,as l8l9, and is of the floating type, being limited in its rotat-ivemovement within the drum only by the anchor pin 20.

The normal direction of rotation of the drum, when the vehicle uponwhich it is installed is moving forwardly, is indicated by the arrow 2i(Figure 1). The webs l8-l9 each carry portions adapted to abut againstthe anchor pin 20, the former being formed with a seat therefor which ismaterially spaced from the free end of the web and the nearest free endof the band. The anchor pin, and the portions carried by the webs l8-l9which seat thereagainst, are shown spaced approximately 45 from the gap22 between the shoe ends. The configuration of the portion 23 of the webIII, which integrally extends beyondthe anchor pin, is clearly shown bythe longer dash lines in Figure 1.

A circumferential extension 24 is also fixedly carried by the end of theweb 19 which abuts the The extension 24 of the web I9 is formed in apair of like sections, one arranged upon each side of the web I9, towhich they are secured, and of the extension 23 of the web l8, which isfreely slidable between them. The sections of the extension 24 may bestamped integrally in channel form from a single piece of stock, thecontour of its spaced sides being best shown in Figure 6, while itscross sectional contour is indicated in Figure 7. The web or big'htportion 26 of the channeled extension 24 is punched out at the pointdesignated 21. Aligned cut-away seat portions 28 are formed upon theends of the side members of the extension, conforming to and adapted tonormally engage the side of the anchor pin 20.

Trunnioned in the opposed sides of the extension 24 adjacent the opening21, as upon stub shaft 29, is a lever 30, connected to the extension 23,as by the link 3|. The ends of the link are enlarged and rounded in theplane of the link, which is flat, and limitedly rotatable in suitablesockets formed in the lever 30 and web extension 23, although thismethod of linkage is of course optional. The shaft 29 may be secured inposition at its inner end by a cotter pin, 32, and the lever 30 securedupon the shaft by forming the aperture therethrough to fit flattenedportions 33 of the shaft. The shaft may extend through the apron 35, andthe operating lever 34 is then secured upon the outer end of the shaft,being apertured to fit over the same, and to engage flats 36 formed uponthe sides of the shaft, upon which it is maintained by heading theshaft, as at 31. The aperture in the apron through which the shaftextends is designated 38, and is preferably protected against theingress of water and other foreign matter, as by forming a. portion(designated 39) of the lever 34 to overlap and cover the same.

The actuating lever 34 is also shown stamped of an integral metallicsheet, the contour to which it is drawn being clearly shown in Figures 1and 2. Its free end will be seen to be provided with an apertured socket46, adapted to receive the complementary half ball head 4i, carried bythe end of the brake actuating cable 42. The socket is slotted, as at41, to enable free pivoting of the lever with respect to the end of thecable, when the brakes are applied and during circumferential movementof the brake band. The cable is shown protected by a conduit 43, theferrule 44 finishing and secured to the end of which is fastened to theapron 35, as by the bracket 45. The details of construction of thecable, conduit etc., forming no part of the present invention, need notbe here set forth in detail. It will be obvious moreover that myimproved brake construction might readily be arranged to be operated byany other mechanical, hydraulic, electrical or other power-applyingmeans.

Also secured upon the shaft 29 within the brake housing formed by thedrum and apron, and here shown as formed integrally with the lever 30,is another lever, 48, which extends through the aperture 21 in the web26 of the channeled extension 24. A hole 49, is punched in the end ofthe lever 48, for the hooked end of the stressed tensile spring 50 whichengages therein. The other extremity of the spring engages an aperture5| in the web l8. It will be seen that the spring 50 thus tends to drawinwardly both ends of the brake band, since the shaft 29 is directly gap22, being shown secured thereto by rivets 25.

supported by the web is, being journaled in the extension 24 thereof. Anadditional tensile spring 52 may be utilized to draw inwardly the servedend of the brake band (that carrying the web I9) with greater force thanthe serving end, although as will presently be explained, this is notessential. The spring 52 is shown secured at one end to a fixedsupporting bracket 53, carried by the apron, and at the other to theextension 24 of the web l9, by insertion of its hooked end in a punchedaperture 54 in the channel web 26.

When the brakes are applied, as by means of a brake pedal or lever, (notshown) a draw upon the cable 42 results. The portion of the brake bandcarried by the web extension 23 is first moved into contact with thedrum, by the above described lever and linkage mechanism. Rotation ofthe drum applies a tangential force to the brake band, which istransmitted therearound causing a piling up action, and a constantlyincreasing radial force which urges the band against the drum. Thebuilding up of the radial. component of the force thus generated islimited at the farther end of the brake shoe by the web l9, to preventundesirable grabbing" of the drum by the shoe.

The generation of radial thrust is relatively smooth and gradual at theserving (first applied) end of the band, but accelerates so rapidly asthe served end is approached as to render desirable the utilization ofsome such stifiening web as l9. It is unduly rapid generation of radialthrust which is undesirable, however, not the evolution of too greatforce. If, therefore, the entire force possible to be thus generatedcould be produced sufiiciently gradually, it could be eifectivelyutilized and controlled. The arrangement of the parts of my improvedbrake construction will be seen to be such that a greater percentage ofsuch radial braking force is built up at the serving end of the brakeshoerelatively slowly-thus furnishing a greater useful braking effort byprolonging the period in which the radial thrust is gradually built up.In the structural embodiment just described, the serving actioncommenced approximately 45 in advance of the anchor pin, and is thentransmitted around the brake shoe to the web [8, the portion of thebrake band carrying which moves as a unit into engagement with the drum.

Figure 12 diagrammatically indicates the comparative functioning of aself-energizing brake incorporating a band construction of my improvedtype, as compared with the more usal servo acting internal expandingbrake band in which the applying means is positioned at the anchor pin,rather than in advance thereof as in my improved construction. Therelative braking effort generated at any given point along the band isin one instance represented by the radial distance between the center Cand the line 56, and in the other by the radial distance to the line 51.The full line 56 represents the braking effort generated in a brake ofmy improved construction, while the dot-dash line 51 comparativelyindicates that developed by the band of an ordinary brake of theself-energizing type. As shown in this figure, in my improved brake theforce begins to build up substantially at the point (A) at which theserving end of the'band is moved into engagement with the drum. Thetangential force subsequently imposed upon the band by rotation of thebrake drum is indicated by arrows 58. The braking effort constitutes theradial travel well around toward the served end before it attainssimilar proportions, at which point it tends to increase too sharply,and must be restricted to prevent undesirable grabbing. The tangentialdirection of the motivating force furnished by the rotating drum will beseen to be largely responsible for the relatively slow increase ofradial thrust adjacent the point of beginning, and it will be similarlyobserved that in mynew construction this radial thrust is neverthelessgiven considerably greater initial extent in which to develop relativelyslowly.

In Figures 8 and 9 I have shown a somewhat modified'construction inwhich the actuating cable is conducted into the interior of the drum,

as through the angularly flanged nipple 44' and the aperture 38' in theapron. In this construc tion the single lever 34' is integrallyextended, as at 30', for connection by means of the link 3i to the webextension 23'. The construction of the stub shaft 29 upon which thelever is journaled in this embodiment is best shown in- 50', as theinward draw which it exerts upon the web portion I9 is reduced by thetendency of the lever to pivot about the cross pin ll carried by the endof the cable, and also by the length of the lever 34'. while the forcewhich it exerts upon the web I8 is directly and fully efl'ective.

Upon applying the brake, the spring 50' continues to draw inwardly theserved end of the band, since the lever pivots about its connection withthe cable, and the spring therefore tends to swing the lever 34' to theleft as viewed in Figure 8, about the axis of the pin H which providesthe pivotal connection between the end of the cable and the hookedextremity 46' of the lever. The extension 24' is thus held against theanchor pin 20' while the web portion I8 is being moved outwardly. Thepin ll transverses the ends of the clevis 4i, which is secured to theend of the cable 42'. The lever 34' swings about the stub shaft 29', andthe integral lever portion 30' urges the section 23' of the band intoengagement with the drum. The shaft 29' meanwhile remains substantiallyfixed in position, andthe extension 24' remains seated against theanchor pin 20' under the influence of the spring 50' until the section23' has contacted the drum, after which continued drawing upon the cabletends to pivot the lever about the end 3| of the link 3 I while the pin25' forces the served end of the brake shoe toward the drum. In thisembodiment it will also be observed that the extension portion 24' isshown pivotally rather than rigidly secured to the web I9, as by meansof the pivot pin 25'. The construction of these parts may otherwise besimilar, however.

In both embodiments, additional support is shown provided for the anchorpin, comprising a bracket (58-55), the construction of which'is clearlyshown in Figures 1, 4 and 8.

To provide automatic take-up means adapted to compensate for wearingaway of the brake lining, and automatically adjust the brakes, I mayemploy the constructions shown in Figures 1, 3, 8, l0 and 11, in oneform of which a series of ratchet teeth 80 are provided upon the outerface of the web I 8-48. The block 8i, formed with complementary ratchetteeth, is yieldably urged laterally against the ratchet teeth Ill by itsspring metal supporting member 82, as shown in Figure 3. The supportingmember 82, is still. enough, however, to resist inward movement of theweb I8 with suflicient firmness. The spring member 62 is supported bymeans of the nut and bolt 63-64, and its rear edge normally seatsagainst the laterally struck-up portion 65 of the apron, which is formedwith a straight locating edge l for such purpose. The aperture 61 in thespring metal supporting member 62. is slightly larger than the stem ofthe bolt 64, as shown in Figure 3, so that the support and the block BImay move outwardly a slight distance upon outward movement of the webI8, when the brake is applied. They of course return to the inward limitof their movement when the brake band is indrawn by the shoe-retractingsprings. The ratchet teeth are of such size and so arranged that theoutward movement of the ratchet toothed section 80 relatively to theblock 6|, upon application of the brake, is through a distance less thanthe length of one ratchet tooth. -Thus, ordinary application of thebrake does not cause the ratchet portions to climb a tooth. When thelining II has worn sufllciently, however, to permit the web I9 to mountone tooth with relation to the block til, it will do so, upon a fullapplication of the brake. The band will then recede from the drum adistance equal to the difierence in the diameters of the stem of thebolt 64 and the aperture 81 in the spring-supporting member 62, or untilthe rear edge'of the supporting member strikes the positioning edge '66,thus providing sufficient clearance, and preventing dragging of thebrake band.

The described automatic adjusting mechanism may also serve as acentering stop for the entire brake band, to prevent the same fromswinging to the left, as viewed in the drawings, about the anchor pin20, which it would do under the influence of the shoe-retracting springor springs, which, as above explained, exertgreater tension upon theserved end of the band. Separate or additional centering means might ofcourse be provided if desired, but since these i'orm no part of mypresent invention they need not herein be further considered.

A somewhat modified form of automatic wearadjusting take-up is shown inFigures 10 and 11, in which, as shown, ratchet teeth I60 are formed uponeach side of the web II9, preferably in substantially aligned opposedrelation and upon an area located at the served end of the band.Complementarily toothed plates ISL-I62 engage the teeth upon each sideof the web, both being supported by the bolt I64, which is secured by anut I63, and provided with apertures [Bl-I68 through which the bolt stempasses. The apertures are preferably slightly larger than the stem ofthe bolt. The compression spring I89, encircling the stem. of the bolt,urges the plate I62 against the toothed section of the web H9. The otherend of the spring bears outwardly against the apron iii. The inner edgeof the plate IBI sufficient distance to enable insertion of the teat I"in the aperture thus formed.

The operation of this form of my self-adjusting mechanism will be seento be similar to that of the first described embodiment. The platesIii-I62 travel outwardly with the web H9 a slight distance uponapplication of the brake, to enable a slight clearance providing returnmovement of the band in event the ratchet sections climb" a tooth. Theteeth are here also preferably slightly longer than the radial distancetraveled by the band in a normal brake application, so that the bandordinarily returns to the same position, until the lining H6 has wornaway sufficiently to cause the automatic taking up of another tooth inthe described manner.

While it will be apparent that the illustrated embodiments of myinvention herein disclosed are well calculated to adequately fulfill theobjects and advantages primarily stated, it is'to be understood that theinvention is susceptible to variation, modification and change withinthe spirit and scope of the subjoined claims.

I claim:

1. In a friction brake, a brake drum, a backing plate having a struckout portion, a brake shoe, means for moving the shoe into engagementwith the drum to apply the brake, braking surfaces carried by the drumand shoe, means normally yieldably holding the shoe away from the drumto maintain the brake in released position, and automatic adjustingmeans to compensate forwearing away of the braking surfaces, comprisinga ratchet toothed portion carried by the shoe, a detentblock yieldablycooperatively engaging the ratchet teeth and abutting said struck outportion to limit movement of the shoe away from the drum but not itsmovement theretoward, the shoe and ratchet section carried thereby beingmovable relatively to the detent block upon normal application of thebrake, through a distance less than the effective distance betweensuccessive ratchet teeth whereby upon release of the brake shoe afterapplication thereof it may ordinarily return to its initial position,but upon sufficient wearing away of the braking surface, the shoecarried ratchet section advances a tooth relatively to the detentmember, which thereby prevents complete return of the shoe to itsinitial position upon release thereof.

2. In a friction brake, a brake drum, a backing plate having a struckout portion, a brake shoe having a radial flange, means for moving theshoe into braking engagement with the drum, braking surfaces carried bythe drum and shoe, means yieldably holding the shoe away from the drumto normally maintain the brake in released position, and automaticadjusting means to compensate for wearing away of the braking surfaces,comprising a ratchet toothed section formed on said flange, a detentblock engaging the ratchet teeth and engaging the struck out portion tolimit movement of the shoe away from the drum but not its movementtheretoward, the shoe and ratchet section being movable relatively tothe block upon an ordinary application of the brake, through a distanceless than the effective distance between successive ratchet teethwhereby upon release of the brake shoe after application thereof it mayordinarily return to its initial position, but upon sufficient wearingaway of the braking surfaces, the shoecarried ratchet section advances atooth relatively to the detent member, which thereby prevents completereturn of the shoe to its initial position, and a stud secured to thebacking plate and extending through the block with clearance forallowing a relatively slight return movement of the shoe after suchadvance of the ratchet, to prevent dragging of the shoe upon the drum.

3. In a friction brake, a brake drum, a backing plate, a brake shoehaving a radial flange engaging said backing plate, means for moving theshoe into engagement with the drum to apply the brake, braking surfacescarrled by the drum and shoe, means normally yieldable holding the shoeaway from the drum to maintain the brake in released position,. andautomatic adjustment means to compensate for wearing away of the brakesurfaces, comprising a ratchet toothed portion formed on said radialflange, a detent plate substantially parallel to the backing plate andhaving one end engaging the ratchet piece and its opposite end abuttingthe backing plate to limit movement of the shoe away from the drum butnot its movement theretoward, a bolt secured to the backing plate andextending with clearance through said detent plate causing it toresiliently engage the radial flange of the shoe and the backing plate,the shoe and ratchet portion carried thereby being movable relativelyto.the detent plate upon normal application of the brake through adistance less than the effective distance between successive ratchetteeth whereby upon release of the brake shoe after application thereofit may ordinarily return to its initial position, but upon sufficientwearing away of the brake surface, the shoe carried ratchet portionadvances a tooth relatively to the detent plate, which thereby preventscomplete return of the shoe to its initial position upon releasethereof.

4. In a friction brake, a brake drum, a backing plate having a struckout portion defining a recess, means for moving the shoe into engagementwith the drum to apply the brake, braking surfaces carried by the drumand shoe, means normally yieldably holding the shoe away from the drumto maintain the brake in release position, and automatic adjusting meansto compensate for wearing away of the braking surfaces, comprising aradial portion of the shoe provided with ratchet teeth on opposite sidesthereof, a pair of detent plates engaging said ratchet teeth, one ofsaid plates abutting said struck out portion to limit movement of theshoe away from the drum but not its movement theretoward, the otherplate having one end received in said recess, a bolt extending withclearance through said plates causing them to engage the radial portionof the shoe, said bolt being secured to said' backing plate and beingprovided with a spring between said backing plate and last named detentplate, the shoe and ratchet section carried thereby being movablerelatively to the detent plates, upon application of the brakes througha distance less than the effective distance between successive ratchetteeth whereby upon release of the brake shoe after application thereof,it may ordinarily return to its initial position, but upon suflicientwearing away of the braking surfaces, the shoe carried ratchet sectionadvances a tooth relatively to the detent member which thereby preventscomplete return of the shoe to its initial position upon releasethereof.

JOHN SNEED.

